1. Field of the Invention
The present invention relates to a bus protocol, and more particularly, to a method and apparatus for a bus interface modified for matching an optical module. The present invention is based on Korean Application No. 99-50595 which is incorporated herein by reference for all purposes.
2. Description of the Related Art
In the field of information processing technology, in which high-speed and miniaturization are important, there are some particular challenges. First, the processing speed of peripheral circuits such as memory, cache memory, and chip sets cannot keep up with that of a high-speed processor. This prevents the processor from performing at its full potential. In addition to this problem in processing speed, there are problems such as noise and electromagnetic interference (EMI). These factors cause problems in the operation of both digital and analog circuits or systems and cause difficulties for users and developers, although there is a difference in the amount of noise or EMI generated in digital and analog circuits.
One method for solving these problems is to transmit data by using an optical medium. This not only allows for high-speed data transmission but can also solve noise or EMI problems. Recently, there have been attempts to solve the problem of making a high-speed data interface using an optical device. However, a data interface using such an optical device is being adopted on only a limited basis due to problems of cost and technology.
In a data transmission using an optical device, a delay time is essentially required for converting optical data into digital data (O-D conversion) and vice versa (D-O conversion). However, the delay time adversely affects high speed data transmission. For example, as the speed of a bus in a computer system increases, the transmission speed of data transmitted through the bus is more greatly influenced by a delay time required for the data conversion.
To solve the above problem, the objectives of the present invention are to provide a bus interface apparatus for matching an optical module, a method therefor, and a peripheral component interconnect (PCI) bus interface for matching an optical module.
Accordingly, to achieve the above objectives, the present invention provides a bus interface apparatus for matching an optical module including: a bus matching unit which performs a control operation for interfacing with the bus, receives digital data and a part of control signals, which are transmitted from the bus, into the bus interface apparatus, and outputs digital data and control signals of the bus interface apparatus, corresponding to the data and the control signals, to the bus; an optical matching module which includes a sending terminal for converting a digital signal to an optical signal to output the optical signal and a receiving terminal for converting an input optical signal to a digital signal; and a matching controller which delays a signal exchanged between the bus matching unit and the optical matching module by a predetermined time to drive the signal, using a predetermined time required for converting a digital signal to an optical signal or vice versa in the optical matching module and signals including a basic synchronization clock signal for operation of the bus.
The matching controller includes a signal receiving means for receiving corresponding control signals of a bus master which intends to write or read data through the bus interface apparatus; and a signal activating means for activating a signal indicating that the bus master can read or write data after at least a predetermined time required for converting a digital signal to an optical signal or vice versa in the optical matching module lapses, when a signal indicating that the bus master is ready to read or write is activated among the control signals.
Alternatively, the matching controller includes a signal receiving means for receiving the basic synchronization clock signal and corresponding control signals of a bus master which intends to write or read data through the bus interface apparatus, and a signal activating means for activating a signal indicating that the bus master can read or write data in synchronization with a change in the state of the basic synchronization clock signal after a predetermined time required for converting a digital signal to an optical signal or vice versa in the optical matching module lapses, when a signal indicating that the bus master is ready to read or write data is activated among the control signals.
The present invention also provides a method of matching an optical module for converting digital data to optical data or vice versa to a bus which operates in synchronization with a basic synchronization clock signal, the method including the steps of: (a) receiving a control signal driven through the optical matching module, the signal being driven by a bus master having a right to use the bus for writing or reading data through the optical matching module; and (b) if the control signal is for writing data, delaying a signal indicating that the bus master can write data by a predetermined time to transmit the signal through the bus.
To achieve another object of the present invention, there is provided a PCI bus interface for matching an optical module including: a PCI bus matching unit which performs a control for interfacing with the PCI bus, receives digital data and a part of control signals transmitted from the PCI bus into the PCI bus interface apparatus, and outputs digital data and control signals of the PCI bus interface apparatus, corresponding to the digital data and the control signals, to the PCI bus; an optical matching module which includes a sending terminal for converting a digital signal to an optical signal to output the optical signal and a receiving terminal for converting an input optical signal to a digital signal; and a matching controller which delays a driving signal indicating that a PCI bus master can write data by a predetermined time to drive the signal, using a predetermined time required for converting a digital signal to an optical signal or vice versa in the optical matching module and signals including a basic synchronization clock signal for operation of the PCI bus, when the bus master having a right to use the PCI bus intends to write data through the interface apparatus.